Augmented reality. It's definitely a buzz phrase, but what is it, exactly? How do you experience it? Is there an app for it? Oh, most definitely. Here are 10.

True to their title, augmented reality apps add something to what you see, using a combination of camera, GPS, and sometimes, in the case of the iPhone 3GS, a compass. The result is something like a real-life heads-up display on your phone, and it's spectacular.

It's been a few months since Apple enabled AR apps in the iPhone's firmware, and as you might expect, there's been an explosion of new takes on the concept. Here are ten of the best:

Note: Most of these apps will work best with the iPhone 3GS, and some explicitly require it. It's worth checking into exactly what you lose without the compass before downloading. Also, here's the article in one page.

Augmented reality. It's definitely a buzz phrase, but what is it, exactly? How do you…
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Layar: Layar was one of the first augmented reality mobile apps to hit any platform, so by the time it made the jump from Android to the iPhone it'd had some time to mature. Layar is an augmented reality framework, not a single purpose app—it's fed by a growing library of "layers," which range from Wikipedia to Flickr to apartment listings in your local town. Plus it's free, so it's a great way to see how the hell this augmented reality thing works in the first place.

Wikitude: Another straightforward overlay app, this one hovers little text bubbles over the locations of geotagged Wikipedia articles. What differentiates this from something like Layar is that through the app's website, Wikitude.me, you can add your own points of interest. Most of the data sets used by AR apps are broad and not that useful outside of large cities, so this is a good way to build your own hyperlocal augmented reality.

Robotvision: A location-based point-of-interest app like Layar or Wikitude, for contrarians. Why? Because it uses Bing local search, like a badass* OK? It's a nice change of pace if you're getting tired of browsing through local historical sites with Wikipedia, or watching local Twitterfiends broadcast their locations every eight minutes. A dollar.

*Person who prefers not to use Google. (You can use Google if you want, too.)

Nearest Subway: Overlays your camera's view with floating, labeled avatars of your nearest subway stations. This one's local to NY, though there are similar apps for other cities (Nearest Tube for London, Bionic Eye for Tokyo, etc). But it doesn't matter, because the experience of actually using this thing borders on sexual, especially if you're used to compass-less Google Maps. Two dollars.

Assassin FPS: Remember that old Kids in the Hall skit, where Mark sits back and pretends to crush everyone's heads with his fingers? This is that, except more modern, less funny and ever-so-slightly sinister. It's essentially an FPS HUD, gun included, superimposed onto real life. You know, so you can shoot your boss in the face because he's got coffee breath, or rocket-blast your wife's silly porcelain dog figurine collection, because you hate her so so so much and wish she would just die, that harpy. Healthy coping, for a dollar!

Pocket Universe: Pocket Universe is a mixed bag. It's not a camera overlay app, so in a way it's the least pure augmented reality app of the bunch. The effect, though, is the same: A compass-equipped iPhone 3GS can use Pocket Universe to display a labeled map of the cosmos matched to wherever it's pointed. It's a heavy-duty astronomy news and reference app in addition to the AR feature, which helps justify the $3 price.

cAR Locator: This concept has been around in one form or another since the advent of GPS in phones, probably because it's extremely simple to execute. Also: useful! Tag your car's location when you get out of it, then later, just point your camera at the parking lot to see your spot. Two dollars, which to be honest. is probably too much.

Yelp: Yelp is my go-to service for new local recommendations in the first place, but the addition of augmented reality adds a layer of whimsy to your typical "where can can a guy get a decent wax job and/or hamburger around here?" adventures. This one's secret—you've got to shake your phone to activate it. Free.

Urbanspoon: Like Yelp, except with an explicit, specific food focus. The augmented reality implementation is much slicker here too: tilt your iPhone down to switch to 2D map mode, and tilt it back up to switch to THE FUTURE. Free.

Junaio: Augmented reality on phones is still a fairly new concept, and most other apps fit a fairly simple template. Junaio is more ambitious, letting users construct 3D scenes in their cameras' viewfinders, place them on a map and share them with others as pictures or as part of explorable layers. The current implementation is kind of rough and the aesthetic is cartoonish, but Junaio captures the spirit of AR better than most. Free.

This week, Gizmodo is exploring the enhanced human future in a segment we call This Cyborg Life. It's about what happens when we treat our body less as a sacred object and more as what it is: Nature's ultimate machine.